Water treatment in Horseshoe Bay, TX starts with the granite the whole town sits on. Stand on the shoreline anywhere in Horseshoe Bay and look at the rock. It is pink. Cap Rock, the dome the ranch families called Goat Rock, and the bald granite the Lupton heirs once considered worthless (now the centerpiece of Lago Escondido) are outcrops of the Llano Uplift, a core of ancient granite and gneiss that breaks the surface here at the southeast corner of the Hill Country. Drive east toward Marble Falls and the ridges grade back into the cream limestone the rest of our service area sits on. That change in the rock is the reason Horseshoe Bay water behaves the way it does, at the faucet and in the few wells on the ranch fringe.
Limestone country gives you aquifers to drill into. Granite country gives you very little, so when the resort opened in 1971 the water had to come from the lake, and it still does. Every home inside the city, and in the MUD subdivisions next door, drinks treated Lake LBJ water. The uplift then decides what is in that water when it reaches your kitchen, and it decides why a private well out here has problems a Trinity well back toward Spicewood would not.
Where the limestone stops
The soil over the granite is thin and rocky, so thin that the city's original mains were laid directly on bedrock. That is what failed at Ferguson Drive and Hi Circle North on December 30, 2022, when an uninsulated pipe burst in the freeze and put Cross Bow, Broken Arrow, No Return and Lighthouse Drive under a boil-water notice. Three creeks, Slick Rock, Horseshoe and Pecan, drain the granite hills north into the lake, and the two springs the old Lupton Ranch relied on sat beside the first two. The lake's normal pool is about 825 feet; the town rises to 883, and the Summit Rock ridge well above that, which is why the 750,000-gallon elevated tower went up there in 2014 and why Summit Rock sits at the top of the system with the longest water age.
For a softener or an RO drain line, the bedrock is a practical matter as well: trenching hits rock fast, so we plan drain routing around what is actually under the slab rather than what a diagram assumes.
A pass-through lake, and what floats down the Llano
Lake LBJ is not a storage reservoir. Wirtz Dam was finished in 1951 (about 653 acres of the Lupton Ranch went under as the lake filled), and the lake holds a near-constant level while the Llano and Colorado rivers flow through it. The city pulls raw water through two intakes under an LCRA contract that doubled to 4,450 acre-feet a year in October 2022 and runs it through 0.1-micron membrane filtration. That is excellent treatment, and in April 2026 the city won Best Tasting Water in Texas for it.
The catch is that a pass-through lake inherits whatever the Llano River brings. The October 2018 flood silted both intakes, discolored the tap water for days, and left enough dissolved organics that the disinfection byproduct TTHM exceeded the federal limit from October 2018 to February 2019, with one sample at 153 parts per billion against a limit of 80. The high reading in 2022 was 73; the 2025 running average at the Summit Rock tower was 45. Summer heat and the July 2026 Llano River flooding pushed organics up again, which is why the city is converting to free chlorine from September 28 to October 27, 2026, to scrub the distribution pipes. Expect a swimming-pool taste for that month.
Lakefront homes on Applehead Island, Matern Island, Pecan Creek and Horseshoe Bay West keep docks in the same water. Any private intake pulling raw lake water needs its own screening, sediment removal and disinfection, which is the surface water treatment side of our work, and the zebra mussels that TPWD lists as fully established in Lake LBJ will foul an unprotected screen.
The last hardness figures the city printed
Membranes do not remove dissolved minerals. The city's own reports put hardness at 167 mg/L in 2018, 175 in 2019 and 195 in 2020, about 10 to 11.4 grains per gallon, hard water on the edge of very hard, with total dissolved solids climbing from 251 to 294 over the same three years. The 2021 through 2025 reports switched to a state template that no longer prints hardness, so those are the last published numbers, not current ones. We read the number at your faucet before sizing anything.
Two other lines from those reports matter in the older houses. Aluminum, carried over from the alum used to settle the lake water, averaged 0.33 mg/L in 2018 against a 0.2 secondary limit, which shows up as white residue. And in 2018 the 90th-percentile lead result was 12 ppb with three homes over the action level: 1970s and 80s copper plumbing in Horseshoe Bay Proper reacting to pH swings. Results have improved since, around 4 ppb in 2023 to 2025, but they are the reason a reverse osmosis system at the kitchen tap is our first recommendation in the Proper: its carbon stages take out chloramine and TTHMs, and the membrane takes out lead and dissolved solids. The chloramine itself, added at about 2 mg/L, wants catalytic carbon at the point of entry; ordinary carbon lets much of it through.
Under the ranch tracts: three formations, three problems
Outside the utility's service area (the acreage south of TX-71 and out along the Blue Lake side), the uplift offers three kinds of well, none of them easy. Ellenburger-San Saba limestone and dolomite gives hard water, compartmentalized by faulting so two neighbors can hit very different quality. The Hickory sandstone carries iron above the secondary limit in its upper section and, according to the Texas Water Development Board, naturally occurring radium, radon and gross alpha that commonly exceed primary drinking-water standards. Fractured granite and gneiss yield under 25 gallons a minute and can quit in a drought.
The treatment follows the formation. Orange staining and a rust taste from a Hickory well call for an air-injection iron filter ahead of any softener. Radium and radon do not show up in a glass; they show up in a lab test, and the fix is RO or ion exchange at the drinking tap. Low-yield granite wells need storage and staged filtration rather than a system that assumes steady flow. On the Burnet County side, exempt wells under about 17 gallons a minute still have to be registered with the Central Texas Groundwater Conservation District. And on septic-scale lots such as Bay Country, Texas law allows a softener to drain to the septic system only if it regenerates on demand.
Condos, second homes and the kitchen tap
Horseshoe Bay's median age is 64.6, nearly half of residents are 65 or older, about 28 percent of the housing is seasonal, and roughly a third of the units are attached homes or condos. Shared risers in resort condos rule out a whole-house softener, so an under-sink RO is the realistic fix there. Second homes are a different question: the city tells returning owners to flush cold taps for several minutes, and a softener or RO left idle for a season needs the same attention, so we schedule around when you are in town. Winter, with irrigation off and the lake at its cleanest, is the easiest window for whole-house work.
The softener question on Lake LBJ water
A water softener in Horseshoe Bay, TX is working against Lake LBJ water that the city's own consumer confidence reports put between 167 and 195 mg/L as calcium carbonate, roughly 10 to 11.4 grains per gallon, hard on the USGS scale and close to very hard. That is why golf-course and lakefront homes here go through fixtures, glass showers and tankless heaters faster than the finish should allow. We install water softeners sized to that hardness and to houses that often sit empty for part of the year, and we pair them with carbon where the chloramine residual is the complaint at the kitchen tap.
West on 71, then RM 2147
We are based in Spicewood, about 27 to 30 road miles east: TX-71 west toward Marble Falls, then RM 2147 into town, roughly 40 minutes to the Proper, with Horseshoe Bay South the closest part of the city to us. Absolute Water Solutions has been at this since 2003, holds TCEQ water treatment license WT001370, is insured, and does every job with its own crews. We install Viqua UV systems for owners who want disinfection on the house side after the boil-water notices of February 2021, October 2021 and December 2022. Business hours are Monday through Friday, 8am to 5pm; request a free estimate online or call (512) 587-8188.